Why did Leonardo often write his thousands of notebook pages using mirror script, from right to left?

Answer

It was a natural habit for a left-hander, likely to avoid smudging ink

Leonardo wrote from right to left as a natural habit for a left-hander, which was likely done to avoid smudging the ink, although it unintentionally added obscurity to the writings.

Why did Leonardo often write his thousands of notebook pages using mirror script, from right to left?

#Videos

Thousands of Pages of Inventions, Ideas and Flying Machines | PBS

I made all of Da Vinci's Inventions! - YouTube

inventordesignmachinerenaissanceda vinci